Simple vs Compound Interest Calculator
Compare simple and compound interest to understand how they affect your money over time.
Initial amount
Annual rate
Duration
How often interest compounds
Simple Interest Total
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Compound Interest Total
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Difference
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Effective APY
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How to Use This Calculator
Step-by-Step Guide
- Enter Principal: The initial amount borrowed or invested.
- Enter Interest Rate: Annual interest rate as a percentage.
- Enter Time Period: Number of years.
- Select Compound Frequency: How often interest compounds.
- Review Results: Compare simple vs compound interest amounts.
Understanding the Difference
- Simple Interest: Interest calculated only on the original principal.
- Compound Interest: Interest calculated on principal plus accumulated interest.
Compound Frequency Options
- Annually: Once per year (typical for some loans)
- Semi-annually: Twice per year (bonds)
- Quarterly: Four times per year (savings accounts)
- Monthly: 12 times per year (most loans)
- Daily: 365 times per year (credit cards)
Why This Matters
Understanding interest types helps you:
- Choose better loan products
- Maximize investment returns
- Compare financial products accurately
- Plan for long-term financial goals
Frequently Asked Questions
Simple interest is calculated only on the principal amount: Principal x Rate x Time. Compound interest is calculated on principal plus accumulated interest. Over time, compound interest grows exponentially faster. Albert Einstein reportedly called compound interest the eighth wonder of the world.
For borrowers, simple interest is better—you pay less total interest. For savers and investors, compound interest is better—you earn more. Credit cards use compound interest (daily), which is why balances grow quickly. Savings accounts use compound interest to help your money grow faster.
Common compounding frequencies: Annually (1x/year), Semi-annually (2x), Quarterly (4x), Monthly (12x), Daily (365x). The more frequent the compounding, the more interest accumulates. Credit cards typically compound daily, which is why paying them off quickly is important.
The Rule of 72 estimates how long it takes money to double: 72 / Interest Rate = Years to Double. At 6% compound interest, money doubles in about 12 years. At 10%, it doubles in about 7.2 years. This rule demonstrates the power of compound interest over time.
Compound interest makes debt grow faster because you are paying interest on interest. A $5,000 credit card balance at 20% APR compounded daily becomes over $6,000 in one year if unpaid. This is why minimum payments keep you in debt for years—always pay more than the minimum on compound interest debts.
Find the Right Business Loan
- Compare 75+ lenders
- Rates as low as 5.49%
- Funding in 24-48 hours
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